Support experiment configurations with/without stability metrics.

components/metrics/file_metrics_provider.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/metrics/file_metrics_provider.h"
 
 #include "base/command_line.h"
 #include "base/files/file.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
@@ skipping 88 matching lines @@
   bool read_complete = false;
 
   // Once a file has been recognized as needing to be read, it is mapped
   // into memory and assigned to an |allocator| object.
   std::unique_ptr<base::PersistentHistogramAllocator> allocator;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SourceInfo);
 };
 
+bool FileMetricsProvider::stability_metrics_enabled_ = true;

[Alexei Svitkine (slow), 2016/11/24 21:27:58]

I don't see where you're using this?

[bcwhite, 2016/11/25 18:51:57]

Doh!  Unsaved file after testing.

+
 FileMetricsProvider::FileMetricsProvider(
     const scoped_refptr<base::TaskRunner>& task_runner,
     PrefService* local_state)
     : task_runner_(task_runner),
       pref_service_(local_state),
       weak_factory_(this) {
 }
 
 FileMetricsProvider::~FileMetricsProvider() {}
 
@@ skipping 425 matching lines @@
 
     // Dump all histograms contained within the source to the snapshot-manager.
     RecordHistogramSnapshotsFromSource(snapshot_manager, source.get());
 
     // Update the last-seen time so it isn't read again unless it changes.
     RecordSourceAsRead(source.get());
   }
 }
 
 }  // namespace metrics